Updated README to reflect slight upsert change

README.md

@@ -323,9 +323,9 @@ db.count({}, function (err, count) {
 * `options` is an object with two possible parameters
   * `multi` (defaults to `false`) which allows the modification of several documents if set to true
   * `upsert` (defaults to `false`) if you want to insert a new document corresponding to the `update` rules if your `query` doesn't match anything
-* `callback` (optional) signature: `err`, `numReplaced`, `upsert`
+* `callback` (optional) signature: `err`, `numReplaced`, `newDoc`
   * `numReplaced` is the number of documents replaced
-  * `upsert` is set to true if the upsert mode was chosen and a document was inserted
+  * `newDoc` is the created document if the upsert mode was chosen and a document was inserted
 
 **Note**: you can't change a document's _id.
 
@@ -373,7 +373,7 @@ db.update({ planet: 'Mars' }, { $unset: { planet: true } }, {}, function () {
 
 // Upserting a document
 db.update({ planet: 'Pluton' }, { planet: 'Pluton', inhabited: false }, { upsert: true }, function (err, numReplaced, upsert) {
-  // numReplaced = 1, upsert = true
+  // numReplaced = 1, upsert = { _id: 'id5', planet: 'Pluton', inhabited: false }
   // A new document { _id: 'id5', planet: 'Pluton', inhabited: false } has been added to the collection
 });